package net.i2p.data.i2np;
/*
 * free (adj.): unencumbered; not under the control of others
 * Written by jrandom in 2003 and released into the public domain
 * with no warranty of any kind, either expressed or implied.
 * It probably won't make your computer catch on fire, or eat
 * your children, but it might.  Use at your own risk.
 *
 */

import net.i2p.I2PAppContext;
import net.i2p.data.DataHelper;

/**
 * Defines the message sent back in reply to a message when requested, containing
 * the private ack id.
 *
 * @author jrandom
 */
public class DeliveryStatusMessage extends FastI2NPMessageImpl {
    public final static int MESSAGE_TYPE = 10;
    private long _id;
    private long _arrival;
    
    /** 4 bytes unsigned */
    private static final long MAX_MSG_ID = (1L << 32) - 1;

    public DeliveryStatusMessage(I2PAppContext context) {
        super(context);
        _id = -1;
        _arrival = -1;
    }
    
    public long getMessageId() { return _id; }

    /**
     *  @param id 0 to (2**32) - 1
     *  @throws IllegalStateException if id previously set, to protect saved checksum
     *  @throws IllegalArgumentException
     */
    public void setMessageId(long id) {
        if (_id >= 0)
            throw new IllegalStateException();
        if (id < 0 || id > MAX_MSG_ID)
            throw new IllegalArgumentException();
        _id = id;
    }
    
    /**
     *  Misnamed, as it is generally (always?) set by the creator to the current time,
     *  in some future usage it could be set on arrival
     */
    public long getArrival() { return _arrival; }

    /**
     *  Misnamed, as it is generally (always?) set by the creator to the current time,
     *  in some future usage it could be set on arrival
     */
    public void setArrival(long arrival) {
        // To accomodate setting on arrival,
        // invalidate the stored checksum instead of throwing ISE
        if (_arrival >= 0)
            _hasChecksum = false;
        _arrival = arrival;
    }
    
    public void readMessage(byte data[], int offset, int dataSize, int type) throws I2NPMessageException {
        if (type != MESSAGE_TYPE) throw new I2NPMessageException("Message type is incorrect for this message");
        int curIndex = offset;
        
        _id = DataHelper.fromLong(data, curIndex, 4);
        curIndex += 4;
        _arrival = DataHelper.fromLong(data, curIndex, DataHelper.DATE_LENGTH);
    }
    
    /** calculate the message body's length (not including the header and footer */
    protected int calculateWrittenLength() { 
        return 4 + DataHelper.DATE_LENGTH; // id + arrival
    }

    /** write the message body to the output array, starting at the given index */
    protected int writeMessageBody(byte out[], int curIndex) throws I2NPMessageException {
        if ( (_id < 0) || (_arrival <= 0) ) throw new I2NPMessageException("Not enough data to write out");
        
        DataHelper.toLong(out, curIndex, 4, _id);
        curIndex += 4;
        DataHelper.toLong(out, curIndex, DataHelper.DATE_LENGTH, _arrival);
        curIndex += DataHelper.DATE_LENGTH;
        return curIndex;
    }
    
    public int getType() { return MESSAGE_TYPE; }
    
    @Override
    public int hashCode() {
        return (int)getMessageId() ^ (int)getArrival();
    }
    
    @Override
    public boolean equals(Object object) {
        if ( (object != null) && (object instanceof DeliveryStatusMessage) ) {
            DeliveryStatusMessage msg = (DeliveryStatusMessage)object;
            return _id == msg.getMessageId() &&
                   _arrival == msg.getArrival();
        } else {
            return false;
        }
    }
    
    @Override
    public String toString() {
        StringBuilder buf = new StringBuilder();
        buf.append("[DeliveryStatusMessage: ");
        buf.append("\n\tMessage ID: ").append(getMessageId());
        buf.append("\n\tArrival: ").append(_context.clock().now() - _arrival);
        buf.append("ms in the past");
        buf.append("]");
        return buf.toString();
    }
}